(1) Field of the Invention
This invention relates to terminal amine-containing polypivalolactones and to their preparation.
(2) Description of the Prior Art
It is known to convert certain .beta.-lactones to polyesters by ring-opening processes. French patent No. 1,231,163 shows polymerization of .alpha.-methyl-.alpha.-ethyl-.beta.-propiolactone and higher homologues by the action of tertiary amines. The polymers are stated to be very high in molecular weight.
Jaacks et al., Die Makromoleculare Chemie, 131, 295-303 (1970) show that treatment of propiolactone or pivalolactone with trimethylamine produces polymers with macrozwitterion structures of the formula EQU (CH.sub.3).sub.3 N.sup.+--(CH.sub.2 CR.sub.2 COO).sub.n --CH.sub.2 CR.sub.2 COO.sup.-
In U.S. Pat. No. 3,897,513 Sundet teaches the preparation of random graft copolymers by reacting a base polymer containing random initiating sites such as free carboxyl groups with a .beta.-lactone such as pivalolactone.
It is also known that graft copolymers and block copolymers can be prepared by condensing a terminal amine-containing polymer such as a nylon polymer chain with a polymer containing free carboxyl groups. It is difficult however to control crosslinking of these copolymers since some of the nylon polymer chains may contain a second terminal amine group which can become a site for crosslinking. Accordingly, it is difficult to maintain the thermoplastic character of these copolymers.